Support .condarc files that don't end in "condarc"?

[jonashaag]

Mamba and Micromamba will not work with a .condarc file given with CONDARC/--rc-file unless it ends in "condarc":

$ micromamba info --rc-file bla 
...
 populated config files :
       libmamba version : 0.19.1
     micromamba version : 0.19.1

...

$ CONDARC=bla mamba info
# Quits immediately, no output

Interestingly this also doesn't work with Conda, which responds with this beauty:

$ CONDARC=bla conda info
[y/N]:
# WAT??

It works if the file ends in "condarc", but not in Micromamba:

$ CONDARC=blacondarc mamba info
...
 populated config files : /opt/homebrew/Caskroom/mambaforge/base/.condarc
                          /Users/j/.condarc
                          /tmp/blacondarc
...

$ micromamba --rc-file blacondarc info
...
 populated config files :
...